1. Field of the Invention
The present invention relates to a snowboard boot, especially of the flexible type particularly adapted for practicing sports such as the "free ride" or "free style."
2. Background and Material Information
Currently, flexible-type boots are essentially designed as mere upwardly extending, impervious and comfortable shoes, but having no actual role in the transmission of forces.
They must be adapted to retaining devices shaped like an open shell having an upwardly extending rear element and a sufficient number of straps to ensure the tightening of the boot to the device. The rear element must be rigid to ensure the rearward support in the so-called "back side" turns. These assemblies have numerous disadvantages. They are very cumbersome due to the straps and the upwardly extending rear support. The straps must be readjusted upon each re-engagement of the shoe in the shell after each climb. The tightening of the straps must be sufficient to retain the boot on the board, which often causes painful constriction spots for the foot in view of the flexibility of the upper. Finally, these shells poorly transmit the bending stresses in all directions, including in rear support, due to an often imprecise adaptation of the rear element to the boot.
The snowboarder who practices the new forms of sport is lead to take supports and adopt a substantially prone forward or rearward posture on the road. He must then strongly bend one of his legs inwardly, in the direction along which a knee is brought closer to the board. The other leg is also subject to a less substantial outward lateral inclination. To facilitate the inward bending of the leg, while maintaining a certain balance, the snowboarder can fold the knee, which generates a rear-to-front bending of the lower the leg.
The document EP-A1-646334 relates to a snowboard boot that includes a flexible inner portion in the form of a shoe, an outer portion also in the form of a shoe, with a flexible upper and a rigid insert arranged between these two portions, a rigid back portion that surrounds the calf being journalled on such insert, at the level of the joint of the foot and of the lower leg, along an axis passing through the longitudinal plane of the shoe.
This shoe has the advantage of making it easy to take the "back side" turns in a very efficient manner due to the rigid back portion inserted directly in the shoe while maintaining a certain lateral looseness, regardless of the interior or medial or exterior or lateral side, to enable the snowboarder to adopt more or less bent positions of the legs. The shoe also maintains the comfort of a flexible-type boot by means of an internal liner and of an external flexible upper. This comfort is particularly appreciated during the use of the shoe for walking. But such a shoe still uses a "shell"-type binding with tightening straps whose disadvantages have been cited hereinabove.
In addition, the shoe according to this invention also have disadvantages that are important factors of dissatisfaction and limit the use thereof. In particular, in view of the position of the journal axis in the median longitudinal plane, only the lateral bending of the leg is actually taken into account. The component of natural forward bending of the lower leg is not particularly favored in view of the rigidity of the insert.
The joint where all the forces and stresses are concentrated is located along the Achilles tendon, which creates a painful spot that is very prejudicial to the comfort of the shoe. The tendon is all the more biased when the snowboarder is in rear support, because the lower portion of the rigid back portion exerts a pressure on the shell toward the interior of the heel under the joint by the effect of the lever.
The problem of comfort generated is increased by the choice of an internal construction of the insert and of the rigid back portion in the immediate vicinity of the foot.
Furthermore, the solution according to the application No. EP-A1-646334 does not provide the necessary external lateral support when the surfer is in the position to rebound his board or in the skating phase, when one of his feet is separated from his board.